Fuel oils such as home heating fuels, automotive fuel oils, gas turbine fuels, and heavy fuels used for industrial heating purposes and for slow and medium speed diesels, as well as lubricating oils for engines and other uses, are susceptible to deterioration during storage, resulting in the formation of insoluble sludge, sediment, and discoloration. The invention is concerned with stabilized fuels and additive compositions for stabilizing such fuel oils. The additives act as combined antioxidants and as dispersants.
A wide variety of additives, especially various amines, have been proposed and widely used to prevent discoloration and sediment formation by interfering with the formation of these colorants or insoluble materials during storage or when thermally stressed, for example, N,N-dimethylcyclohexyl amine, U.S. Pat. No. 3,490,882. Other additives are described in U.S. Pat. Nos. 3,186,810, and 2,737,452 for use in fuel oils and U.S. Pat. No. 2,737,496 for use in lubricating oils. These additives use diethyl aminoethylmethacrylate, styrene and alkylmethacrylate.
A variety of polymeric materials have also been proposed and widely used to prevent sedimentation of insoluble sludge by dispersant action. These materials generally do not prevent the formation of color or insoluble material but prevent detrimental effects such as clogged filters, nozzles, injectors, heat exchangers, and fouling of other parts of fuel distribution or use systems with insoluble sludge formed during storage or by thermal stressing. However, ideal oil additives have not been found. Improvements are always needed.
Group transfer polymerization is known to be useful for producing acrylic and methacrylic polymers having desirable features.
O. W. Webster, U.S. Pat. No. 4,417,034 (Nov. 22, 1983) and U.S. Pat. No. 4,508,880 (Apr. 2, 1985), and W. B. Farnham and D. Y. Sogah, U.S. Pat. No. 4,414,372 (Nov. 8, 1983) and U.S. Pat. No. 4,524,196 (June 18, 1985) showed that acrylic copolymers can be prepared via group transfer polymerization. (GTP). GTP applications and techniques have also been described in European Patent Application No. 184,692, Quirk et al., published June 18, 1986, and in the literature including F. Bandermann and H. Speikamp (of the Institute fur Technische Chemie, UniversitatGesamthochschule Essen) "Group Transfer polymerization of Methyl Methacrylate" Makromol. Chem., Rapid Commun. 6,335-339 (1985). Oxyanion catalysts for GTP processes are described in U.S. Pat. No. 4,588,795, Dicker et al., granted May 13, 1986. AB block copolymers of acrylics and oxirane-containing acrylics are the subject of U.S. Pat. No. 4,656,226 issued Apr. 7, 1987 Hutchins et al. Polymers made by GTP have been suggested to be generally useable as oil additives in U.S. patent application Ser. No. 4,656,226 issued Apr. 7, 1987.
U.S. Pat. No. 4,388,448, Melby, discusses low temperature anionic polymerization to make epoxy block copolymers.
The above patents and publications are incorporated herein by reference.